Alberto Gonzales, the US attorney general, is struggling to hang on to his job after a disastrous performance before the Senate judicial committee investigating the sacking of eight federal prosecutors. Yesterday's appearance had been viewed as a make-or-break moment for Mr Gonzales, a member of George Bush's inner circle since his days in Texas, who stands accused of politicising the judiciary.

By late afternoon, it looked as if Mr Gonzales, despite his insistence that he had done nothing wrong, and saw no need to resign, was being dragged towards the exit after two previously supportive Republican senators called for him to stand down.

"I believe the best way to put this behind us is your resignation," said Tom Coburn of Oklahoma, describing the justice department's handling of the sackings as "incompetent" and "atrocious".

Two other Republican senators came close to calling Mr Gonzales a liar in his justification of the sackings, and in his own role in the actions. He did not help his cause by his faltering testimony, exposing fresh inconsistencies in his description of the process leading to the sackings.

In one low point, Mr Gonzales claimed he could not remember attending a crucial meeting last November 10 days before the dismissals - one of more than 40 occasions yesterday where he uttered the words, "I can't recall".

At another, he reversed a previous statement that he had not discussed the prosecutors with the White House. "I now understand there was a conversation with myself and the president," he said.

The senators did not hide their frustration. "Why is your story changing?" asked Charles Grassley, a Republican from Iowa.

The only bright note for Mr Gonzales came from the White House, which said George Bush had been pleased with the day's events. "After hours of testimony in which he answered all of the senators' questions and provided thousands of pages of documents, he again showed that nothing improper occurred," the statement said.

However, it was unclear whether the show of support would provide the lifeline Mr Gonzales needed.

One of the prosecutors was allegedly sacked to block a politically awkward corruption investigation involving a Republican Congressman from California. In another, a prosecutor in New Mexico was reportedly fired because he refused to pursue an investigation into voter fraud demanded by a Republican senator.

During yesterday's questioning, Mr Gonzales admitted that he had conversations on at least two occasions with the White House political supremo, Karl Rove, and a Republican senator about the sacking of a prosecutor in New Mexico.

That undermined his mission to convince critics that politics played no part in the dismissals, and that he was being truthful in his earlier claims to have played only a limited role in those decisions.

"Most of this is a stretch," a Republican senator, Lindsey Graham, said after listening to Mr Gonzales justify the dismissals. "It's clear to me that some of these people just had personality conflicts with people in your office or the White House, and [they] just made up reasons to fire them."